Gas turbine engines, such as those used to provide thrust to an aircraft, are internal combustion engines that use air as the working fluid. In general, gas turbine engines may include a fan section and a core engine located downstream of the fan section. In operation, air may be drawn into the engine and accelerated by the fan section, and a fraction of the indrawn air may be routed through the core engine where the air may be combusted with fuel to provide energy to drive the engine and provide forward thrust to an associated aircraft, or power if used in land based operations. In an upstream to downstream order, the core engine may include a compressor section, one or more combustors, a turbine section, and an exhaust nozzle.
The fan section, the compressor section, and the turbine section may each include rotating airfoils (e.g., blades). The overall efficiency of gas turbine engines may be dependent on the formation of a tight seal between the tips of the blades and an abradable seal radially outward of the blade tips. The seal may be established by allowing the tips of the blades to cut into or abrade the abradable seal, thereby preventing air/gas from leaking past the blade tip. In particular, the blade tips may cut the seal to match the rotation path of the blade tips.
Blade tips in gas turbine engines may have a rough, abrasive surface to promote effective cutting into the abradable material. Alternatively, they may have a hard, wear-resistant coating such as an alumina or a zirconia coating. Current gas turbine engine designs may employ cubic boron nitride (CBN) particles to create a rough surface on the tips of the blades due to the favorable cutting properties of CBN. For example, U.S. Pat. No. 5,704,759 describes the attachment of CBN particles to the tips of compressor blades via an entrapment electroplating process. Similarly, U.S. Patent Application Publication Number 2005/0129511 describes turbine blade tips having abrasive coatings that include a mixture of CBN particles and silicon nitride (Si3N4) particles. Other prior art methods for producing abrasive tips on gas turbine engine blades may rely on brazing or thermal spray deposition.
While effective, current abrasive blade tips, such and CBN-based abrasive tips, may be expensive to manufacture. Furthermore, current methods for producing abrasive blade tips may require multiple steps including a grinding step to size the blade tips to length, followed by a thermal spray or plating process to apply the abrasive to a heavily masked blade.
Thus, there is a need for more cost-effective and efficient manufacturing methods for gas turbine engine parts having abrasive surfaces.